bin/35622: sigaltstack is missing in libc_r

[Daniel Eischen]

On Mon, 2 Feb 2004, Craig Rodrigues wrote:

> The following reply was made to PR bin/35622; it has been noted by GNATS.
> 
> From: Craig Rodrigues <rodrigc at crodrigues.org>
> To: freebsd-gnats-submit at freebsd.org
> Cc: michiel.dewilde at rug.ac.be
> Subject: Re: bin/35622: sigaltstack is missing in libc_r
> Date: Mon, 2 Feb 2004 16:48:14 -0500
> 
>  Hi,
>  
>  In FreeBSD-CURRENT, libc_r does not have a symbol
>  for sigaltstack which overrides the symbol in libc.

libc_r was built around the 96 POSIX spec that said that
use of sigaltstack in a threaded program was undefined.

>  However, the new libpthread does have such a symbol.

The new 200x POXIC spec allows sigaltstack() so David
added it to libpthread.  It is mostly for threads bound
to kernel scheduleable entities, and use of it otherwise
is undefined.  Don't tell anyone, but libpthread does
allow it even for scope process threads.